Troilism was coined in the 1941 edition of Dorland's Medical Dictionary where it was classified as a paraphilia. It was not clear why this scientific name was chosen.

One examination of the word may indicate a root in the French word trois (three). A similar French term, triolisme, exists in French—the shift between the third and fourth letter is perhaps a mistake. On the other hand, ménage à trois (household of three) was coined in the late 19th century. Although all those terms involve three people, ménage à trois implies a romantic link between all three, which is quite different from troilistic scenarios. In French, a plan à trois, vulgar form and synonym of triolisme, corresponds more closely to a troilistic scenario; a "threesome".[citation needed]